Madison— Gov. Scott Walker staked the legacy of his short presidential run on an appeal to his GOP rivals to follow him, bow out and give those remaining a clear shot at front-runner Donald Trump.

So far, not a single other Republican in the crowded field has dropped out. And in Walker's home state of Wisconsin, his supporters in the presidential race are more likely to support Trump than any of the alternatives that the governor had hoped to boost.

In dropping out Sept. 21, Walker said he was "being called to lead by helping to clear the field in this race." Two weeks later, no one else is answering this call, at least not yet.

Instead, the remaining 15 candidates are picking off Walker's fundraisers and supporters to try to sustain their own campaigns.

"Walker's appeal hasn't gotten any support and it was unrealistic to think it would. Instead, it gave some candidates new life as the courtship of Walker's supporters, donors and operatives got underway," said Jennifer Duffy, a senior editor at the Cook Political Report.

Faced with plummeting polling and a dwindling supply of cash, Walker was seeking to salvage value from a once-promising campaign that turned out to be one of the shortest on record, undone by excessive spending and the unexpected rise of outsider candidates like Trump.

But he was the second Republican to drop out, following former Texas Gov. Rick Perry. In suspending his campaign, Walker set a clear goal for leaving the race.

"I encourage other Republican presidential candidates to consider doing the same so that the voters can focus on a limited number of candidates who can offer a positive conservative alternative to the current front-runner," Walker said.

But other GOP candidates who haven't caught on in the polls — and likely never will — are still around: politicians such as Louisiana Gov. Bobby Jindal, U.S. Sen. Lindsay Graham of South Carolina and former New York Gov. George Pataki.

"There are four or five who need to bow out. Why they don't is a mystery to me," said Steffen Schmidt, a political science professor at Iowa State University.

But Schmidt said he did know why Walker's appeal to other candidates has fallen flat, saying that no one wants to "follow a loser."

"I have asked and everyone made fun of his call to fall on the hand grenade. They said he was 'leading from behind — in the polls!'" Schmidt said.

Touring a manufacturing company in Mequon on Friday, Walker said other candidates would eventually follow suit.

"Well, I don't think it was a matter of happening all within a week or two," Walker said. "I think between now and the first ballots being cast February 1, I would imagine there would be others that will do that between now and then."

Withdrawing early from a race has worked for the governor before. When he dropped out of the 2006 GOP primary for governor in Wisconsin, Walker gained goodwill from his fellow Republicans and made his successful 2010 run possible.

But there are big differences between this presidential race and the previous race for Wisconsin governor. Republicans have a huge field for 2016 and at the time Walker exited the race, he was drawing virtually no support in the polls.

In 2006, only one Republican, then-U.S. Rep. Mark Green, was vying with Walker to be the party's nominee for governor and Walker, though trailing by key measures, was widely seen to be running a competitive race.

With so little support from voters at the moment of his exit last month, Walker had less to offer those candidates who remain.

The governor has left open the possibility that he'll endorse one of them. But for now the field is so large and unsettled that it's no surprise that Walker hasn't picked a candidate or even given the names of those who he feels offer a "positive" alternative to Trump. Former Florida Gov. Jeb Bush and U.S. Sen. Marco Rubio of Florida are seen as two possibilities.

In Wisconsin, the latest Marquette University poll showed the largest share of Walker's supporters going to Trump — the opposite of what the governor had hoped.

But that's not necessarily the case elsewhere.

In Iowa, Public Policy Polling, a Democratic survey firm, reported that Walker supporters now prefer former neurosurgeon Ben Carson over Trump 68% to 26%; Rubio over Trump 66% to 31%; former Hewlett-Packard executive Carly Fiorina over Trump 59% to 28%; and Bush over Trump 48% to 36%.

In the end, the main resource that Walker had to offer his Republican rivals was his people — his staff and those who had endorsed and raised funds for him. The fight for that human capital began even before Walker made his formal withdrawal.

Randy Feenstra, a GOP state senator from Iowa who backed Walker, has shifted to U.S. Sen. Ted Cruz of Texas.

Anthony Scaramucci, a New York investor who had served as Walker's national finance co-chairman, went to Bush's campaign. Minneapolis broadcasting billionaire Stanley Hubbard, a former Walker donor, has said he's looking at donating to Rubio, Fiorina and New Jersey Gov. Chris Christie.

For now, cash will be a decisive factor for candidates mulling whether to continue, as Walker said it was for him.

"People don't stop running for president because they run out of ideas or they run out of a desire to give speeches," Terry Sullivan, Rubio's campaign manager, said last month. "They stop running because they run out of money."

The Associated Press and Mary Spicuzza of the Journal Sentinel staff contributed to this article.

About Jason Stein

Jason Stein covers the state Capitol and is the author with his colleague Patrick Marley of "More than They Bargained For: Scott Walker, Unions and the Fight for Wisconsin." His work has been recognized by journalism groups such as the American Society of News Editors, the Society of American Business Editors and Writers, and the Association of Capitol Reporters and Editors.